1. Field of the Invention
The present invention relates to a stator, a motor and a method of manufacturing such a stator.
Priority is claimed on Japanese Patent Applications Nos. 2005-055670, 2005-055671, and 2005-055672 filed Mar. 1, 2005; Japanese Patent Applications Nos. 2005-057141 and 2005-057142 filed Mar. 2, 2005; and Japanese Patent Applications Nos. 2005-306778, 2005-306779, and 2005-306780 filed Oct. 21, 2005, the contents of which are incorporated herein by reference.
2. Description of Related Art
There is conventionally known a claw pole motor with a stator having a U-phase stator ring, a V-phase stator ring, and a W-phase stator ring disposed so as to be coaxially superimposed in the direction of the axis, annular coils forming a rotating magnetic field that rotates a rotor, the annual coils being disposed in annular coil mounting portions formed between the adjacent stator rings in the axial direction, and provided with claw poles extending radially from the stator rings of each phase, the claw poles of each phase arranged in the circumferential direction and opposing the magnetic poles of the stator (see, for example, Japanese Unexamined Patent Application, First Publication No. 2005-20981).
There is conventionally known a three-phase motor that drives a rotor in three phases with a stator having coils of each of the three phases U, V, and W being concentrically wound on stator cores of the three phases (see, for example, Japanese Unexamined Patent Application, First Publication No. H07-227075).
Also, there is known a three-phase motor that drives a rotor in three phases with a stator wound with coils of a U-phase, V-phase, and W-phase that traverse the circumference in a corrugated shape by weaving between adjacent teeth (see, for example, Japanese Unexamined Patent Application, First Publication No. 2002-165396).
In the claw pole motor according to the aforementioned prior art, a U-phase coil and first V-phase coil are disposed in annular coil mounting portions between the U-phase stator ring and V-phase stator ring that are adjacent in the axial direction, and a second V-phase coil and a W-phase coil are disposed in annular coil mounting portions between the V-phase stator ring and W-phase stator ring that are adjacent in the axial direction. Therefore, comparing the number of windings in each phase, the number of windings of the V-phase is double the number of windings of the U-phase and W-phase. The inductance of the V-phase therefore differs from the inductances of the U-phase and W-phase. This inductance mismatch ends up complicating control of the claw pole motor.
In the three-phase motors according to the aforementioned prior art, since a winding is required for each of the three phases, it is difficult to avoid an increase in the number of parts required for constitution of the stator, and cumbersome work is required for winding the coils of each phase.
Moreover, in a stator in which the coils are wound by corrugated winding, it is difficult to improve the winding space factor between adjacent teeth, and moreover it is difficult to lower the height of the coil end to reduce the dimensions in the axial direction of the motor and enhance the mounting property on a vehicle.
For this reason, it is desired to reduce the number of parts by simplifying the structure of the stator and simplifying the manufacturing process of the stator, and also reduce the dimensions in the axial direction of the motor by lowering the height of the coil end while improving the winding space factor in the stator to enhance the mounting property of the motor on a vehicle.